The present invention is directed to article sorters and, in particular, to positive displacement sorters in which pusher shoes traveling with the conveying surface selectively laterally displace articles on the conveying surface such as to a selected spur.
In one type of positive displacement sorter, such as disclosed in commonly assigned U.S. Pat. No. 5,127,510, the web defining the conveying surface is made up of a plurality of slats that are connected at opposite ends to endless chains. The pusher shoes travel laterally along one or more slats. Wheels mounted to the chain support the web. The chains are driven by motor driven chain sprockets which propel the web.
In another type of positive displacement sorter, such as disclosed in commonly assigned U.S. Pat. No. 6,814,216, the web defining the conveying surface is made up of a plurality of slats that are each supported by one or more wheels supporting each slat and members interconnecting adjacent slats. The pusher shoes travel laterally along one or more slats. The web is driven by a linear motor system made up of motor primaries distributed beneath the web and secondary plates attached to the slats.